Multi-material component and methods of making thereof

ABSTRACT

A multi-material component joined by a high entropy alloy is provided, as well as methods of making a multi-material component by joining materials with high entropy alloys to reduce or eliminate liquid metal embrittlement (LME) cracks.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/660,025, entitled “MULTI-MATERIAL COMPONENT AND METHODS OFMAKING THEREOF,” filed on Jul. 26, 2017, which claims benefit to U.S.Provisional Patent Application Ser. No. 62/371,032 entitled“MULTI-MATERIAL COMPONENT AND METHODS OF MAKING THEREOF, AND ACONSUMABLE WELDING FILLER AND METHODS OF MAKING AND USING THEREOF,”filed on Aug. 4, 2016, U.S. Provisional Patent Application Ser. No.62/395,790, entitled “MULTI-MATERIAL COMPONENT AND METHODS OF MAKINGTHEREOF, AND A CONSUMABLE WELDING FILLER AND METHODS OF MAKING AND USINGTHEREOF,” filed on Sep. 16, 2016, and U.S. Provisional PatentApplication Ser. No. 62/525,314 entitled “MULTI-MATERIAL COMPONENT ANDMETHODS OF MAKING THEREOF,” filed on Jun. 27, 2017. This applicationalso claims benefit to U.S. Provisional Patent Application Ser. No.62/802,556, entitled “MULTI-MATERIAL COMPONENT AND METHODS OF MAKINGTHEREOF,” filed Feb. 7, 2019; U.S. Provisional Patent Application Ser.No. 62/833,435, entitled MULTI-MATERIAL COMPONENT AND METHODS OF MAKINGTHEREOF,” filed Apr. 12, 2019, and U.S. Provisional Patent ApplicationSer. No. 62/933,076, entitled MULTI-MATERIAL COMPONENT AND METHODS OFMAKING THEREOF,” filed Nov. 8, 2019. The disclosure of each above-notedapplication is incorporated herein by reference.

BACKGROUND

The substitution of lightweight metals or metal alloys for low-carbonsteel or other types of steel used in motor vehicles is an attractiveoption for vehicle mass reduction. Often, however, the remainder of thevehicle body structure is fabricated of a dissimilar material. Thejoining of dissimilar materials can be problematic due to thedifferences in physical and metallurgical properties between the twodifferent metals. For example, joining an aluminum or aluminum-basedalloy to steel can result in the formation of intermetallic compoundswhich deteriorate the mechanical properties of the joint and causecorrosion issues, and therefore, requires additional manufacturing stepsor safeguards to prevent mechanical strength degradation and galvaniccorrosion.

In addition, when resistance spot welding is used to join iron or steelparts having a zinc (Zn)-containing coating, such as galvanized and/orgalvannealed iron or steel, to other iron or steel parts and/or todissimilar materials, the low melting point of the coating, as well asthe applied load by the welding electrodes, may cause diffusion of Zninto the iron and/or steel, leading to liquid metal embrittlement (LME)cracking.

SUMMARY

In general, a high entropy alloy (HEA) is provided that may be used forjoining dissimilar or similar metals or metal alloys, wherein one ormore of the metal or metal alloys comprises iron and/or steel with acoating, wherein the coating comprises Zn (alternatively referred toherein as a “Zn coating”). According to some aspects, the Zn coating maybe a metal or metal alloy coating that comprises more than about 50% w/wof a metal or metal alloy, optionally more than about 75% w/w,optionally more than about 90% w/w, optionally more than about 95% w/w,and optionally more than about 99% w/w. According to some aspects, theZn coating may consist of a metal or metal alloy. According to someaspects, the Zn coating may correspond with the coating of a materialthat has been galvanized and/or galvannealed. According to some aspects,an HEA is provided that may be used for joining a first iron and/orsteel having a Zn coating with a second iron and/or steel, optionallyhaving a Zn coating, and/or for joining a first iron and/or steel havinga Zn coating with another metal or metal alloy. High entropy alloyspromote formation of solid solution and prohibit intermetallicsespecially at high temperatures. As a result, the high entropy alloysprovide mechanical strength and corrosion resistance of the weldingjoint for joining dissimilar materials. The high entropy alloys mayadditionally or alternatively reduce the diffusion of zinc into ironand/or steel during resistance spot welding processes, which may reduceor eliminate LME cracking.

In accordance with one embodiment, a multi-material component isprovided that includes a first member comprising a metal or a metalalloy, particularly iron and/or steel having a Zn coating, a secondmember comprising a metal or a metal alloy, which may or may not be ironand/or steel having a Zn coating, and a third member joining the firstmember to the second member. The third member comprises a high entropyalloy. Optionally, the metal or metal alloy of the first member isdifferent than the metal or metal alloy of the second member.Optionally, the high entropy alloy comprises a first principal elementthat is the same as the metal or a base metal of the first member.Optionally, the high entropy alloy comprises a second principal elementthat is the same as the metal or a base metal of the second member.Optionally, the first member comprises an aluminum alloy and the secondmember comprises steel. Optionally, the first member and/or the secondmember each independently comprises iron and/or steel having a Zncoating, and the multi-material component is substantially free of LMEcracking.

Optionally, the high entropy alloy comprises Al and Fe as principalelements. Optionally, the high entropy alloy comprises Al, Fe, and Mn asprincipal elements. Optionally, the high entropy alloy comprises atleast Fe as a principal element. Optionally, the high entropy alloycomprises at least Mn as a principal element. Optionally, the highentropy alloy comprises at least Ni as a principal element. Optionally,the high entropy alloy comprises at least Co as a principal element.Optionally, the high entropy alloy comprises at least Zn as a principalelement. Optionally, the high entropy alloy comprises at least Cu as aprincipal element. Optionally, the high entropy alloy comprises at leastCr as a principal element.

Optionally, the high entropy alloy comprises four principal elements.Optionally, the high entropy alloy comprises five principal elements.Optionally, the high entropy alloy comprises six principal elements.Optionally, the high entropy alloy comprises seven or more principalelements. According to some aspects, one or more of the principalelements may be principal minor elements. Optionally, the high entropyalloy comprises five or more principal elements including: Al, Fe, Mn,Cr, and Ni. Optionally, the high entropy alloy comprises four or moreprincipal elements including Cu, Co, and/or Zn. Optionally, the highentropy alloy comprises five, six, seven, or more principal elementsincluding Cu, Co, and/or Zn. Optionally, the high entropy alloycomprises at least four principal major elements selected from the groupconsisting of Fe, Mn, Ni, Co, Cu, and Cr, and optionally Zn as a fifthprincipal element, which may be present as a principal major element ora principal minor element.

In accordance with one embodiment, a method of making a multi-materialcomponent is provided that includes providing a first member comprisinga metal or a metal alloy as described herein, providing a second membercomprising a metal or a metal alloy as described herein, positioning athird member at least partially between the first member and the secondmember, and joining the first member and the second member to the thirdmember. The third member comprises a high entropy alloy. Optionally, thefirst member and the second member are joined to the third member bywelding. Optionally, the metal or metal alloy of the first member isdifferent than the metal or metal alloy of the second member.Optionally, the high entropy alloy comprises a first principal elementthat is the same as the metal or a base metal of the first member.Optionally, the high entropy alloy comprises a second principal elementthat is the same as the metal or a base metal of the second member.Optionally, the first member comprises an aluminum alloy and the secondmember comprises steel. Optionally, the first member comprises ironand/or steel having a Zn coating. Optionally, the second membercomprises iron and/or steel, optionally having a Zn coating, wherein thesecond member is formed from the same material as the first member or isformed from a different material from the first member.

Optionally, the high entropy alloy comprises Al and Fe as principalelements. Optionally, the high entropy alloy comprises Al, Fe, and Mn asprincipal elements. Optionally, the high entropy alloy comprises atleast Fe as a principal element. Optionally, the high entropy alloycomprises at least Mn as a principal element. Optionally, the highentropy alloy comprises at least Ni as a principal element. Optionally,the high entropy alloy comprises at least Co as a principal element.Optionally, the high entropy alloy comprises at least Zn as a principalelement. Optionally, the high entropy alloy comprises at least Cu as aprincipal element. Optionally, the high entropy alloy comprises at leastCr as a principal element.

Optionally, the high entropy alloy comprises four principal elements.Optionally, the high entropy alloy comprises five principal elements.Optionally, the high entropy alloy comprises six principal elements.Optionally, the high entropy alloy comprises seven or more principalelements. According to some aspects, one or more of the principalelements may be principal minor elements. Optionally, the high entropyalloy comprises five or more principal elements including: Al, Fe, Mn,Cr, and Ni. Optionally, the high entropy alloy comprises at least fourprincipal major elements selected from the group consisting of Fe, Mn,Ni, Co, Cu, and Cr, and optionally Zn as a fifth principal element,which may be present as a principal major element or a principal minorelement.

In accordance with one embodiment, a method of making a multi-materialcomponent is provided that includes providing a first member comprisinga metal or a metal alloy as described herein, providing a second membercomprising a metal or a metal alloy as described herein, and joining thefirst member to the second member with a material comprising a highentropy alloy as described herein or a high entropy alloy precursorcomposition that forms a high entropy alloy as described herein whenmelted. The joining step may include welding the first member to thesecond member with the material, or cladding the material over the firstmember and the second member. Optionally, the metal or metal alloy ofthe first member is different than the metal or metal alloy of thesecond member. Optionally, the high entropy alloy comprises a firstprincipal element that is the same as the metal or a base metal of thefirst member. Optionally, the high entropy alloy comprises a secondprincipal element that is the same as the metal or a base metal of thesecond member. Optionally, the first member comprises an aluminum alloyand the second member comprises steel. Optionally, the first membercomprises iron and/or steel having a Zn coating. Optionally, the secondmember comprises iron and/or steel, optionally having a Zn coating,wherein the second member is formed from the same material as the firstmember or is formed from a different material from the first member.

In accordance with one embodiment, a welding consumable is provided thatincludes a filler material comprising a high entropy alloy as describedherein or a high entropy alloy precursor composition capable of forminga high entropy alloy as described herein when welded.

In accordance with one embodiment, a multi-material component isprovided that includes a first member comprising a metal or a metalalloy as described herein, a second member comprising a metal or a metalalloy as described herein, including a metal or metal alloy having a Zncoating as described herein, wherein the second member comprises a metalor a metal alloy as described herein that is the same as or differentfrom the metal or the metal alloy of the first member, and a thirdmember joining the first member to the second member, wherein the thirdmember comprises a high entropy alloy. Optionally, the high entropyalloy may comprise a mixing entropy of greater than 1.3R, and optionallymay comprise a mixing entropy of greater than 1.5R.

Optionally, the high entropy alloy as described above comprises at leastfour elements each present in the high entropy alloy in an amount offrom 5 to 35 atomic %. Optionally two of the at least four elements thatare each present in the high entropy alloy in an amount of from 5 to 35atomic % comprise Fe and Cr and the amount of the Fe and Cr vary by nomore than 5 atomic % with respect to each other, optionally two of theat least four elements that are each present in the high entropy alloyin an amount of from 5 to 35 atomic % comprise Fe and Ni and the amountof the Fe and Ni vary by no more than 5 atomic % with respect to eachother, optionally two of the at least four elements that are eachpresent in the high entropy alloy in an amount of from 5 to 35 atomic %comprise Cr and Ni and the amount of the Ni and Cr vary by no more than5 atomic % with respect to each other, optionally two of the at leastfour elements that are each present in the high entropy alloy in anamount of from 5 to 35 atomic % comprise Fe and Al and the amount of theFe and Al vary by no more than 5 atomic % with respect to each other,optionally two of the at least four elements that are each present inthe high entropy alloy in an amount of from 5 to 35 atomic % comprise Aland Ni and the amount of the Al and Ni vary by no more than 5 atomic %with respect to each other, optionally two of the at least four elementsthat are each present in the high entropy alloy in an amount of from 5to 35 atomic % comprise Al and Cr and the amount of the Al and Cr varyby no more than 5 atomic % with respect to each other, optionally two ofthe at least four elements that are each present in the high entropyalloy in an amount of from 5 to 35 atomic % comprise Cu and Co, and theamount of the Cu and Co vary by no more than 5 atomic % with respect toeach other, optionally two of the at least four elements that are eachpresent in the high entropy alloy in an amount of from 5 to 35 atomic %comprise Cu and Zn, and the amount of the Cu and Zn vary by no more than5 atomic % with respect to each other, and optionally two of the atleast four elements that are each present in the high entropy alloy inan amount of from 5 to 35 atomic % comprise Co and Zn, and the amount ofthe Co and Zn vary by no more than 5 atomic % with respect to eachother.

Optionally, the high entropy alloy as described above comprises at leastfive elements each present in the high entropy alloy in an amount offrom 5 to 35 atomic %. Optionally two of the at least five elements thatare each present in the high entropy alloy in an amount of from 5 to 35atomic % comprise Fe and Cr and the amount of the Fe and Cr vary by nomore than 5 atomic % with respect to each other, optionally two of theat least five elements that are each present in the high entropy alloyin an amount of from 5 to 35 atomic % comprise Fe and Ni and the amountof the Fe and Ni vary by no more than 5 atomic % with respect to eachother, optionally two of the at least five elements that are eachpresent in the high entropy alloy in an amount of from 5 to 35 atomic %comprise Cr and Ni and the amount of the Ni and Cr vary by no more than5 atomic % with respect to each other, optionally two of the at leastfive elements that are each present in the high entropy alloy in anamount of from 5 to 35 atomic % comprise Fe and Al and the amount of theFe and Al vary by no more than 5 atomic % with respect to each other,optionally two of the at least five elements that are each present inthe high entropy alloy in an amount of from 5 to 35 atomic % comprise Aland Ni and the amount of the Al and Ni vary by no more than 5 atomic %with respect to each other, optionally two of the at least five elementsthat are each present in the high entropy alloy in an amount of from 5to 35 atomic % comprise Al and Cr and the amount of the Al and Cr varyby no more than 5 atomic % with respect to each other, optionally two ofthe at least five elements that are each present in the high entropyalloy in an amount of from 5 to 35 atomic % comprise Cu and Co, and theamount of the Cu and Co vary by no more than 5 atomic % with respect toeach other, optionally two of the at least five elements that are eachpresent in the high entropy alloy in an amount of from 5 to 35 atomic %comprise Cu and Zn, and the amount of the Cu and Zn vary by no more than5 atomic % with respect to each other, and optionally two of the atleast five elements that are each present in the high entropy alloy inan amount of from 5 to 35 atomic % comprise Co and Zn, and the amount ofthe Co and Zn vary by no more than 5 atomic % with respect to eachother.

Optionally, the high entropy alloy as described above comprises at leastsix elements each present in the high entropy alloy in an amount of from5 to 35 atomic %. Optionally two of the at least six elements that areeach present in the high entropy alloy in an amount of from 5 to 35atomic % comprise Fe and Cr and the amount of the Fe and Cr vary by nomore than 5 atomic % with respect to each other, optionally two of theat least six elements that are each present in the high entropy alloy inan amount of from 5 to 35 atomic % comprise Fe and Ni and the amount ofthe Fe and Ni vary by no more than 5 atomic % with respect to eachother, optionally two of the at least six elements that are each presentin the high entropy alloy in an amount of from 5 to 35 atomic % compriseCr and Ni and the amount of the Ni and Cr vary by no more than 5 atomic% with respect to each other, optionally two of the at least sixelements that are each present in the high entropy alloy in an amount offrom 5 to 35 atomic % comprise Fe and Al and the amount of the Fe and Alvary by no more than 5 atomic % with respect to each other, optionallytwo of the at least six elements that are each present in the highentropy alloy in an amount of from 5 to 35 atomic % comprise Al and Niand the amount of the Al and Ni vary by no more than 5 atomic % withrespect to each other, optionally two of the at least six elements thatare each present in the high entropy alloy in an amount of from 5 to 35atomic % comprise Al and Cr and the amount of the Al and Cr vary by nomore than 5 atomic % with respect to each other, optionally two of theat least six elements that are each present in the high entropy alloy inan amount of from 5 to 35 atomic % comprise Cu and Co, and the amount ofthe Cu and Co vary by no more than 5 atomic % with respect to eachother, optionally two of the at least six elements that are each presentin the high entropy alloy in an amount of from 5 to 35 atomic % compriseCu and Zn, and the amount of the Cu and Zn vary by no more than 5 atomic% with respect to each other, and optionally two of the at least sixelements that are each present in the high entropy alloy in an amount offrom 5 to 35 atomic % comprise Co and Zn, and the amount of the Co andZn vary by no more than 5 atomic % with respect to each other.

Optionally, the high entropy alloy as described above comprises at leastseven elements each present in the high entropy alloy in an amount offrom 5 to 35 atomic %. Optionally two of the at least seven elementsthat are each present in the high entropy alloy in an amount of from 5to 35 atomic % comprise Fe and Cr and the amount of the Fe and Cr varyby no more than 5 atomic % with respect to each other, optionally two ofthe at least seven elements that are each present in the high entropyalloy in an amount of from 5 to 35 atomic % comprise Fe and Ni and theamount of the Fe and Ni vary by no more than 5 atomic % with respect toeach other, optionally two of the at least seven elements that are eachpresent in the high entropy alloy in an amount of from 5 to 35 atomic %comprise Cr and Ni and the amount of the Ni and Cr vary by no more than5 atomic % with respect to each other, optionally two of the at leastseven elements that are each present in the high entropy alloy in anamount of from 5 to 35 atomic % comprise Fe and Al and the amount of theFe and Al vary by no more than 5 atomic % with respect to each other,optionally two of the at least seven elements that are each present inthe high entropy alloy in an amount of from 5 to 35 atomic % comprise Aland Ni and the amount of the Al and Ni vary by no more than 5 atomic %with respect to each other, optionally two of the at least sevenelements that are each present in the high entropy alloy in an amount offrom 5 to 35 atomic % comprise Al and Cr and the amount of the Al and Crvary by no more than 5 atomic % with respect to each other, optionallytwo of the at least seven elements that are each present in the highentropy alloy in an amount of from 5 to 35 atomic % comprise Cu and Co,and the amount of the Cu and Co vary by no more than 5 atomic % withrespect to each other, optionally two of the at least seven elementsthat are each present in the high entropy alloy in an amount of from 5to 35 atomic % comprise Cu and Zn, and the amount of the Cu and Zn varyby no more than 5 atomic % with respect to each other, and optionallytwo of the at least seven elements that are each present in the highentropy alloy in an amount of from 5 to 35 atomic % comprise Co and Zn,and the amount of the Co and Zn vary by no more than 5 atomic % withrespect to each other.

Optionally three of the at least four elements that are each present inthe high entropy alloy in an amount of from 5 to 35 atomic % compriseFe, Ni, and Cr and the amount of the Fe, Ni, and Cr vary by no more than5 atomic % with respect to each other, optionally three of the at leastfour elements that are each present in the high entropy alloy in anamount of from 5 to 35 atomic % comprise Fe, Al, and Ni and the amountof the Fe, Al, and Ni vary by no more than 5 atomic % with respect toeach other, optionally three of the at least four elements that are eachpresent in the high entropy alloy in an amount of from 5 to 35 atomic %comprise Al, Cr, and Ni and the amount of the Al, Ni, and Cr vary by nomore than 5 atomic % with respect to each other, optionally three of theat least four elements that are each present in the high entropy alloyin an amount of from 5 to 35 atomic % comprise Fe, Cr, and Al and theamount of the Fe, Cr, and Al vary by no more than 5 atomic % withrespect to each other, and optionally three of the at least fourelements that are each present in the high entropy alloy in an amount offrom 5 to 35 atomic % comprise Cu, Co, and Zn and the amount of the Cu,Co, and Zn vary by no more than 5 atomic % with respect to each other.

Optionally three of the at least five elements that are each present inthe high entropy alloy in an amount of from 5 to 35 atomic % compriseFe, Ni, and Cr and the amount of the Fe, Ni, and Cr vary by no more than5 atomic % with respect to each other, optionally three of the at leastfive elements that are each present in the high entropy alloy in anamount of from 5 to 35 atomic % comprise Fe, Al, and Ni and the amountof the Fe, Al, and Ni vary by no more than 5 atomic % with respect toeach other, optionally three of the at least five elements that are eachpresent in the high entropy alloy in an amount of from 5 to 35 atomic %comprise Al, Cr, and Ni and the amount of the Al, Ni, and Cr vary by nomore than 5 atomic % with respect to each other, optionally three of theat least five elements that are each present in the high entropy alloyin an amount of from 5 to 35 atomic % comprise Fe, Cr, and Al and theamount of the Fe, Cr, and Al vary by no more than 5 atomic % withrespect to each other, and optionally three of the at least fiveelements that are each present in the high entropy alloy in an amount offrom 5 to 35 atomic % comprise Cu, Co, and Zn and the amount of the Cu,Co, and Zn vary by no more than 5 atomic % with respect to each other.

Optionally three of the at least six elements that are each present inthe high entropy alloy in an amount of from 5 to 35 atomic % compriseFe, Ni, and Cr and the amount of the Fe, Ni, and Cr vary by no more than5 atomic % with respect to each other, optionally three of the at leastsix elements that are each present in the high entropy alloy in anamount of from 5 to 35 atomic % comprise Fe, Al, and Ni and the amountof the Fe, Al, and Ni vary by no more than 5 atomic % with respect toeach other, optionally three of the at least six elements that are eachpresent in the high entropy alloy in an amount of from 5 to 35 atomic %comprise Al, Cr, and Ni and the amount of the Al, Ni, and Cr vary by nomore than 5 atomic % with respect to each other, optionally three of theat least six elements that are each present in the high entropy alloy inan amount of from 5 to 35 atomic % comprise Fe, Cr, and Al and theamount of the Fe, Cr, and Al vary by no more than 5 atomic % withrespect to each other, and optionally three of the at least six elementsthat are each present in the high entropy alloy in an amount of from 5to 35 atomic % comprise Cu, Co, and Zn and the amount of the Cu, Co, andZn vary by no more than 5 atomic % with respect to each other.

Optionally three of the at least seven elements that are each present inthe high entropy alloy in an amount of from 5 to 35 atomic % compriseFe, Ni, and Cr and the amount of the Fe, Ni, and Cr vary by no more than5 atomic % with respect to each other, optionally three of the at leastseven elements that are each present in the high entropy alloy in anamount of from 5 to 35 atomic % comprise Fe, Al, and Ni and the amountof the Fe, Al, and Ni vary by no more than 5 atomic % with respect toeach other, optionally three of the at least seven elements that areeach present in the high entropy alloy in an amount of from 5 to 35atomic % comprise Al, Cr, and Ni and the amount of the Al, Ni, and Crvary by no more than 5 atomic % with respect to each other, optionallythree of the at least seven elements that are each present in the highentropy alloy in an amount of from 5 to 35 atomic % comprise Fe, Cr, andAl and the amount of the Fe, Cr, and Al vary by no more than 5 atomic %with respect to each other, and optionally three of the at least sevenelements that are each present in the high entropy alloy in an amount offrom 5 to 35 atomic % comprise Cu, Co, and Zn and the amount of the Cu,Co, and Zn vary by no more than 5 atomic % with respect to each other.

Optionally, the high entropy alloy comprises at least four principalmajor elements. Optionally, the high entropy alloy comprises at leastfive principal major elements. Optionally, the high entropy alloycomprises at least six principal major elements. Optionally, the highentropy alloy comprises at least seven principal major elements. As usedherein, the term “principal major element” refers to a principal elementpresent at a concentration of at least 5 atomic %.

Optionally, the at least four principal major elements may be selectedfrom the group consisting of Fe, Mn, Ni, Co, Cu, and Cr, wherein theamount of at least two of the principal major elements vary by no morethan 5 atomic % with respect to each other, optionally wherein theamount of at least three of the principal major elements vary by no morethan 5 atomic % with respect to each other, optionally wherein theamount of at least four of the principal major elements vary by no morethan 5 atomic % with respect to each other, optionally wherein theamount of at least five of the principal major elements vary by no morethan 5 atomic % with respect to each other, optionally wherein theamount of at least six of the principal major elements vary by no morethan 5 atomic % with respect to each other, and optionally wherein theamount of at least seven of the principal major elements vary by no morethan 5 atomic % with respect to each other.

Optionally, the high entropy alloy comprises at least five principalmajor elements. Optionally, the at least five principal major elementsmay be selected from the group consisting of Fe, Mn, Ni, Co, Cu, Cr, andZn, wherein the amount of at least two of the principal major elementsvary by no more than 5 atomic % with respect to each other, optionallywherein the amount of at least three of the principal major elementsvary by no more than 5 atomic % with respect to each other, optionallywherein the amount of at least four of the principal major elements varyby no more than 5 atomic % with respect to each other, optionallywherein the amount of at least five of the principal major elements varyby no more than 5 atomic % with respect to each other, optionallywherein the amount of at least six of the principal major elements varyby no more than 5 atomic % with respect to each other, and optionallywherein the amount of at least seven of the principal major elementsvary by no more than 5 atomic % with respect to each other.

Optionally, the high entropy alloy comprises at least six principalmajor elements. Optionally, the at least six principal major elementsmay be selected from the group consisting of Fe, Mn, Ni, Co, Cu, Cr, andZn, wherein the amount of at least two of the principal major elementsvary by no more than 5 atomic % with respect to each other, optionallywherein the amount of at least three of the principal major elementsvary by no more than 5 atomic % with respect to each other, optionallywherein the amount of at least four of the principal major elements varyby no more than 5 atomic % with respect to each other, optionallywherein the amount of at least six of the principal major elements varyby no more than 5 atomic % with respect to each other, optionallywherein the amount of at least six of the principal major elements varyby no more than 5 atomic % with respect to each other, and optionallywherein the amount of at least seven of the principal major elementsvary by no more than 5 atomic % with respect to each other.

Optionally, the high entropy alloy comprises at least seven principalmajor elements. Optionally, the at least seven principal major elementsmay be selected from the group consisting of Fe, Mn, Ni, Co, Cu, Cr, andZn, wherein the amount of at least two of the principal major elementsvary by no more than 5 atomic % with respect to each other, optionallywherein the amount of at least three of the principal major elementsvary by no more than 5 atomic % with respect to each other, optionallywherein the amount of at least four of the principal major elements varyby no more than 5 atomic % with respect to each other, optionallywherein the amount of at least seven of the principal major elementsvary by no more than 5 atomic % with respect to each other, optionallywherein the amount of at least seven of the principal major elementsvary by no more than 5 atomic % with respect to each other, andoptionally wherein the amount of at least seven of the principal majorelements vary by no more than 5 atomic % with respect to each other.

In one example, the high entropy alloy comprises at least Fe as aprincipal major element. In one example, the high entropy alloycomprises at least Mn as a principal major element. In one example, thehigh entropy alloy comprises at least Ni as a principal major element.In one example, the high entropy alloy comprises at least Co as aprincipal major element. In one example, the high entropy alloycomprises at least Cu as a principal major element. In one example, thehigh entropy alloy comprises at least Cr as a principal major element.In one example, the high entropy alloy comprises at least Zn as aprincipal major element.

In one example, the high entropy alloy comprises at least Fe and Mn asprincipal major elements. In one example, the high entropy alloycomprises at least Fe and Ni as principal major elements. In oneexample, the high entropy alloy comprises at least Fe and Co asprincipal major elements. In one example, the high entropy alloycomprises at least Fe and Cu as principal major elements. In oneexample, the high entropy alloy comprises at least Fe and Cr asprincipal major elements. In one example, the high entropy alloycomprises at least Cu and Co as principal major elements. In oneexample, the high entropy alloy comprises at least Cu and Zn asprincipal major elements. In one example, the high entropy alloycomprises at least Co and Zn as principal major elements.

In one example, the high entropy alloy comprises at least Fe, Mn, and Nias principal major elements. In one example, the high entropy alloycomprises at least Fe, Mn, and Co as principal major elements. In oneexample, the high entropy alloy comprises at least Fe, Mn, and Cu asprincipal major elements. In one example, the high entropy alloycomprises at least Fe, Mn, and Cr as principal major elements. In oneexample, the high entropy alloy comprises at least Cu, Co, and Zn asprincipal major elements.

In one example, the high entropy alloy comprises at least Fe, Ni, and Coas principal major elements. In one example, the high entropy alloycomprises at least Fe, Ni, and Cu as principal major elements. In oneexample, the high entropy alloy comprises at least Fe, Ni, and Cr asprincipal major elements. In one example, the high entropy alloycomprises at least Fe, Cu, and Co as principal major elements. In oneexample, the high entropy alloy comprises at least Fe, Cu, and Zn asprincipal major elements. In one example, the high entropy alloycomprises at least Fe, Co, and Zn as principal major elements.

In one example, the high entropy alloy comprises Fe, Mn, Ni, and Co asprincipal major elements. In one example, the high entropy alloycomprises Fe, Mn, Ni, and Cu as principal major elements. In oneexample, the high entropy alloy comprises Fe, Mn, Co, and Cu asprincipal major elements. In one example, the high entropy alloycomprises Fe, Mn, Cr, and Ni as principal major elements. In oneexample, the high entropy alloy comprises Fe, Mn, Cu, and Co asprincipal major elements. In one example, the high entropy alloycomprises Fe, Mn, Cu, and Zn as principal major elements. In oneexample, the high entropy alloy comprises Fe, Mn, Co, and Zn asprincipal major elements.

In one example, the high entropy alloy comprises Fe, Ni, Co, and Cu asprincipal major elements. In one example, the high entropy alloycomprises Fe, Ni, Cu, and Co as principal major elements. In oneexample, the high entropy alloy comprises Fe, Ni, Cu, and Zn asprincipal major elements. In one example, the high entropy alloycomprises Fe, Ni, Co, and Zn as principal major elements.

In one example, the high entropy alloy comprises Fe, Mn, Ni, Co, and Znas principal major elements. In one example, the high entropy alloycomprises Fe, Mn, Ni, Cu, and Zn as principal major elements. In oneexample, the high entropy alloy comprises Fe, Mn, Co, Cu, and Zn asprincipal major elements. In one example, the high entropy alloycomprises Fe, Mn, Cr, Ni, and Zn as principal major elements. In oneexample, the high entropy alloy comprises Fe, Mn, Cu, Co, and Zn asprincipal major elements. In one example, the high entropy alloycomprises Fe, Ni, Co, Cu, and Zn as principal major elements. In oneexample, the high entropy alloy comprises Fe, Ni, Cu, Co, and Zn asprincipal major elements.

In one example, the high entropy alloy comprises Al, Fe, Mn, Cr, and Cuas principal major elements. In one example, the high entropy alloycomprises Fe, Mn, Ni, Co, and Cu as principal major elements. In oneexample, the high entropy alloy comprises Mn, Ni, Co, Cu, and Zn asprincipal major elements. In one example, the high entropy alloycomprises Fe, Mn, Ni, Cr, Co, Cu, and Zn as principal major elements. Inone example, the high entropy alloy comprises Al, Fe, Mn, Ni, Cr, Cu,and Zn as principal major elements.

Optionally, the high entropy alloy comprises at least one principalminor element. As used herein, the term “principal minor element” refersto a principal element present at a concentration of less than 5 atomic%. Optionally, the high entropy alloy comprises at least two principalmajor elements and one principle minor element, optionally at leastthree principal major elements and one principle minor element,optionally at least four principal major elements and one principleminor element, optionally at least five principal major elements and oneprinciple minor element, optionally at least six principal majorelements and one principle minor element, and optionally at least sevenprincipal major elements and one principle minor element. Optionally,the high entropy alloy comprises any combination of principal majorelements as described herein and Zn as a principal minor element.

In accordance with one embodiment, a method of making a multi-materialcomponent is provided that includes providing a first member comprisinga metal or a metal alloy as described herein, providing a second membercomprising a metal or a metal alloy, optionally wherein the secondmember comprises a metal or a metal alloy that is different from themetal or metal alloy of the first member, and joining the first memberto the second member with a third member comprising a high entropy alloyas described herein to form the multi-material component. Optionally,the step of joining the first member to the second member with the thirdmember includes positioning the third member between the first memberand the second member, and spot welding the first member to the thirdmember and spot welding the second member to the third member.Optionally, the third member is a consumable material and the step ofjoining the first member to the second member with the third membercomprises: melting the consumable material to deposit the high entropyalloy as described herein on the first member and the second member.Optionally, the high entropy alloy as described herein may comprise amixing entropy of greater than 1.3R, and optionally may comprise amixing entropy of greater than 1.5 R.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a multi-material component joined by spot weldingaccording to one aspect of the present disclosure.

FIG. 2 illustrates a cross-sectional view of an exemplary multi-materialcomponent according to one aspect of the present disclosure.

FIGS. 3A and 3B illustrate welding consumables comprising a high entropyalloy according to one aspect of the present disclosure.

FIG. 4 illustrates a diagram of a laser system for brazing, cladding,building up, filling, hard-facing, overlaying, welding, and joiningapplications with a high entropy alloy according to one aspect of thepresent disclosure.

FIG. 5 illustrates a diagram of a gas metal arc welding system forbrazing, cladding, building up, filling, hard-facing, overlaying,welding, and joining applications with a high entropy alloy according toone aspect of the present disclosure.

FIG. 6 illustrates a diagram of a gas tungsten arc welding system forbrazing, cladding, building up, filling, hard-facing, overlaying,welding, and joining applications with a high entropy alloy according toone aspect of the present disclosure.

FIG. 7A illustrates a laser cladding system that uses a wire weldingconsumable for depositing a high entropy alloy on a substrate.

FIG. 7B illustrates a laser cladding system that uses a powder weldingconsumable for depositing a high entropy alloy on a substrate.

FIG. 8 illustrates a functional schematic block diagram of a combinationwire welding consumable feeder and energy source system for any ofbrazing, cladding, building up, filling, hard-facing, overlaying,welding, and joining applications with a high entropy alloy according toone aspect of the present disclosure.

FIGS. 9A and 9B illustrate a B-pillar of a vehicle secured to a roofrail of the vehicle.

FIG. 10 shows the load (KN) vs. displacement (mm) for each samplestudied in the Tensile-Sear Test described in Example I.

FIG. 11 shows the optical macrographs of the fracture surface and topsurface of the weld spots of the upper steel sheet of samples N-1, N-2,and N-3, as described in Example II.

FIG. 12A shows the optical macrographs of the fracture surface and topsurface of the weld spots of the upper steel sheet of samples H-1, H-2,and H-3, as described in Example II.

FIG. 12B shows a magnified portion of the top surface of the weld spotof sample H-2 in FIG. 12A.

FIG. 13 is a schematic showing the tensile stress axis relative to thedemonstrated plan views shown in FIGS. 11, 12, 15, and 16.

FIG. 14A shows the load (k. N) vs. displacement (mm) for each samplestudied in the Tensile-Sear Test described in Example III

FIG. 14B shows the average fracture load for the two sets of sampleswith and without HEA interlayer.

FIG. 15 shows the two fracture surfaces of the four samples without HEAinterlayer as described in Example III.

FIG. 16 shows the two fracture surfaces of the four samples with HEAinterlayer as described in Example III.

FIG. 17 shows a phase diagram as described in Example V.

FIG. 18 shows a Scheil solidification diagram as described in Example V.

FIG. 19 shows the chemical composition of gamma phase as described inExample V.

FIG. 20A shows the initial chemical composition profile as described inExample VI.

FIG. 20B shows the thermal profile for the diffusion modelling asdescribed in Example VI.

FIG. 21A shows the diffusion behavior of the HEA, specifically thecomposition profile after diffusion simulation, as described in ExampleVI.

FIG. 21B shows the diffusion behavior of the HEA, specifically thepredicted phases, as described in Example VI.

FIG. 22A shows the diffusion behavior of the Zn—Fe couple, specificallythe composition profile after diffusion simulation, as described inExample VI.

FIG. 22B shows the diffusion behavior of the Zn—Fe couple, specificallythe predicted phases, as described in Example VI.

FIG. 23 shows the diffusion behavior of the HEA vs. steel, specifically,the composition profile after diffusion simulation, as described inExample VII.

FIG. 24A shows a photograph of two cross sections of the control sampleas described in Example VIII.

FIG. 24B shows optical micrograph images of the control sample asdescribed in Example VIII.

FIG. 25A shows a photograph of two cross sections of the inventivesample as described in Example VIII.

FIG. 25B shows optical micrograph images of the inventive sample asdescribed in Example VIII.

DETAILED DESCRIPTION

It should be understood that the description and drawings herein aremerely illustrative and that various modifications and changes can bemade in the compositions, methods and structures disclosed withoutdeparting from the present disclosure.

In general, a high entropy alloy is provided for the joining of metalsor metal alloys. As used herein, the term “high entropy alloy” refersgenerally to an alloy comprising four or more principal major elementsas described herein having a mixing entropy of greater than 1.3R,wherein the entropy of mixing is determined using the equationΔSmix=R1nN, wherein R is the gas constant and N is the total number ofelements. The high entropy alloy may comprise equiatomic or nearequiatomic of multiple principal elements as described herein. Highentropy alloys promote formation of a solid solution and prohibitintermetallics especially at high temperatures. Accordingly, thestructure of the solution phases is simply face-centered cubic (FCC) orbody centered cubic (BCC) or a combination of the two, as opposed to amulti-phase structure, which is typically seen in conventional alloymaterials. In an illustrative example, the high entropy alloy comprisesa single phase solid solution with an FCC crystal structure. Such highentropy alloys may have unique physical and mechanical propertiesbecause they still have simple crystal structure but their lattices arehighly distorted due to atomic size misfit. The structure can also beadjusted by changing the composition level, i.e. it can be transferredfrom FCC to BCC while increasing the amount of, for example, Al contentin an aluminum-containing high entropy alloy. The solid solution phasesof the high entropy alloys are stabilized by the significantly highentropy of mixing compared with intermetallic compounds, especially athigh temperatures.

As described herein, the entropy of mixing can be determined using theequation ΔSmix=R1nN, where R is the gas constant and N is the totalnumber of elements. The value of the mixing entropy reaches a maximumvalue when the composition is near equi-atomic. In a non-limitingexample, the high entropy alloy may comprise four or more principalelements, optionally five principal elements, having a mixing entropy(ΔSmix) of greater than 1.3R where R is a gas constant (8.314 J/K mole).Optionally, the high entropy alloy may comprise four or more principalelements, optionally five principal elements, having a ΔSmix of greaterthan 1.5R. In a non-limiting example, the high entropy alloy maycomprise four or more principal elements, optionally five principalelements, and the principal elements may each comprise from 5 to 90atomic % of the high entropy alloy, and optionally the high entropyalloy may comprise at least four principal elements, optionally fiveprincipal elements, with each principal element present in an amount offrom 5 to 35 atomic % of the high entropy alloy. Principal elements mayinclude, but are not limited to, Fe, Co, Ni, Hf, Si, B, Cu, Al, Mg, W,Ta, Nb, Cr, Sn, Zr, Ti, Pd, Au, Pt, Ag, Ru, Mo, V, Re, Bi, Cd, Pb, Ge,Sb, Zn, and Mn. For example, the high entropy alloy may comprise twomore of, optionally three or more of, optionally four or more of,optionally five or more of, optionally six or more of, and optionallyseven of more of Al: 5-90 atomic %, Fe: 5-90 atomic %, Mn: 5-90 atomic%, Ni: 5-90 atomic %, Cr: 5-90 atomic %, Co: 5-90 atomic %, Cu: 5-90atomic %, and Zn: 5-90 atomic %. Optionally, the high entropy alloy mayfurther comprise one or more principal minor elements in an amount ofless than 5 atomic %. In one illustrative example, the high entropyalloy comprises Zn as a principal minor element. Optionally, the highentropy alloy may comprise at least four or more principal elementswherein at least four of the principal elements each comprise from 5 to35 atomic % of the high entropy alloy. In an illustrative example, thehigh entropy alloy comprises four or more of: Al: 5-35 atomic %, Fe:5-35 atomic %, Mn: 5-35 atomic %, Ni: 5-35 atomic %, Cr: 5-35 atomic %Co: 5-90 atomic %, Cu: 5-90 atomic %, and Zn: 5-90 atomic %.

The principal elements of the high entropy alloy may be present in anequimolar amount, or in a near-equimolar amount. Optionally, at leastfour of the principal elements of the high entropy alloy may be presentin an equimolar amount, or in a near-equimolar amount. In a non-limitingexample, relative amounts of each (or optionally two, three, four, orfive of the) principal element(s) in the high entropy alloy varies nomore than 15 atomic %, no more than 10 atomic %, or no more than 5atomic %. In an illustrative example, the high entropy alloy comprisesat least four principal elements, the at least four principal elementsof the high entropy alloy comprise at least 90 atomic % of the highentropy alloy, and the relative amounts of at least four principalelements of the high entropy alloy vary by no more than 5 atomic %, suchas a high entropy alloy that comprises Al, Fe, Mn, Ni, Cr, Co, Cu,and/or Zn. For example, the high entropy alloy may comprise fiveprincipal elements and the relative amounts of each of the principalelements in the high entropy alloy varies no more than 5 atomic %, suchas a high entropy alloy that comprises Al, Fe, Mn, Ni, Cr, Co, Cu,and/or Zn.

The high entropy alloy may consist only of principal elements except forimpurities ordinarily associated with the principal elements or methodsof making the high entropy alloy. Optionally, the high entropy alloy maycontain one or more principal minor elements each comprising less than 5atomic % of the high entropy alloy. Illustrative examples include Fe,Co, Ni, Hf, Si, B, Cu, Al, Mg, W, Ta, Nb, Cr, Sn, Zr, Ti, Pd, Au, Pt,Ag, Ru, Mo, V, Re, Bi, Cd, Pb, Ge, Sb, Mn, Zn, and mixtures thereof. Inan illustrative example, the total amount of principal minor elementspresent in the high entropy alloy is less than or equal to 30 atomic %,optionally less than equal to 20 atomic %, optionally less than or equalto 10 atomic %, optionally less than 5 atomic %, optionally less than2.5 atomic %, or optionally less than 1.0 atomic %.

The principal elements of the high entropy alloy may comprise at least70 atomic % of the high entropy alloy, optionally at least 80 atomic %of the high entropy alloy, optionally at least 90 atomic % of the highentropy alloy, and optionally at least 95 atomic % of the high entropyalloy. In a non-limiting example, the principal elements of the highentropy alloy may comprise from 85 atomic % to 95 atomic % of the highentropy alloy.

The high entropy alloy can be formed by a variety of methods including,but not limited to, melting and casting, forging, or powder metallurgy.In a non-limiting example, the high entropy alloy may be produced byusing liquid-phase methods include arc melting and induction melting, byusing solid-state processing such as the use of a high-energy ball mill,gas-phase processing including sputtering, or by thermal spraying, lasercladding, or electrodeposition.

FIGS. 1-9B provide illustrative examples of multi-material componentsjoined by the high entropy alloys of the present disclosure, methods ofjoining multi-material components with the high entropy alloys of thepresent disclosure, and welding consumables comprising the high entropyalloys or precursors of the high entropy alloys of the presentdisclosure.

As shown in FIG. 1, a multi-material component 5 may be provided thatincludes a first member 10 comprising a metal or a metal alloy includinga base metal, a second member 20 comprising a metal or a metal alloyincluding a base metal, and a third member 30 joining the first member10 to the second member 20. The metal or metal alloy of the first member10 may be different than the metal or metal alloy of the second member20, or the metal or metal alloy of the first member 10 may be the sameas the metal or metal allot of the second member 20. In an illustrativeexample, the first member 10 comprises an aluminum alloy and the secondmember 20 comprises steel. In another illustrative example, both thefirst member 10 and the second member comprise steel. In anotherillustrative example, both the first member 10 and the second member 20comprise iron. In another illustrative example, one of the first member10 and the second member 20 comprises steel and the other of the firstmember 10 and the second member 20 comprises iron. It should beunderstood that either or both of the first member 10 and the secondmember 20 comprise a Zn coating as described herein. The third member 30comprises the high entropy alloy and may be entirely or at leastpartially positioned between the first member 10 and the second member20. The third member 30 may be in the form of a plate, a sheet, a foil,or the like, and the first member 10 and the second member 20 may bejoined to the third member 30 by one or more welds, mechanicalfasteners, adhesives, or any combination thereof. Optionally, the thirdmember 30 may be in the form of a coating or cladding on one or both ofthe first member 10 and the second member 20. Accordingly, the thirdmember 30 may be at least partially positioned between the first member10 and the second member 20 to provide physical separation therebetweenand function as an insulator to facilitate reduction of the galvanicpotential between the first member 10 and the second member 20. In anon-limiting example, the first member 10 and the second member 20 arespot welded to the third member 30 with electrodes of a resistance spotwelding device 40. In a non-limiting example, the third member 30 may bein the form of a sheet or a foil strip that has a thickness of from 0.10mm to 1.0 mm, optionally from 0.15 mm to 0.6 mm, optionally from 0.25 mmto 0.5 mm, and optionally 0.4 mm. In another non-limiting example, thethird member may have a thickness of between about 1 and 1000 μm,optionally between about 25 and 750 μm, optionally between about 50 and500 μm, optionally between about 50 and 250 μm, and optionally betweenabout 75 and 500 μm. Optionally, the third member consists only of thehigh entropy alloy.

It is to be understood that the third member 30 may be secured to thefirst member 10 or the second member 20 prior to the spot weldingoperation. In an illustrative example, the third member 30 is secured tothe first member 10, the first member 10 is then positioned opposite thesecond member 20 with the third member 30 positioned between the firstmember 10 and the second member 20, followed by the spot weldingoperation that forms a weld nugget that extends through a portion ofeach of the first member 10, the second member 20, and the third member30 to join or otherwise secure the first member 10 to the second member20 to form the multi-material component 5. It is to be understood thatthe third member 30 may be secured to the first member 10 or the secondmember 20 using any suitable method. Illustrative examples includeadhesives, mechanical fasteners, welds, and cladding of the third member30 to one or both of the first member 10 and the second member 20.

Although FIG. 1 includes only a single third member 30 for joining thefirst member 10 to the second member 20, it is to be understood that anynumber of third members 30 may be positioned between the first member 10and the second member 20 for the purposes of joining (such as by spotwelding) the first member 10 to the second member 20. It is also to beunderstood that the third member 30 may comprise more than one highentropy alloy. In an illustrative example, the third member 30 maycomprise a first high entropy alloy that is particularly suitable forjoining (such as spot welding) to the first member 10 and a second highentropy alloy that is a different alloy than the first high entropyalloy and is particularly suitable for joining (such as spot welding) tothe second member 20. In such a configuration, the third member 30 maycomprise a laminate with the first high entropy alloy bonded (such aswith an adhesive) to the second high entropy alloy. In anothernon-limiting example, the first high entropy alloy may be secured to thefirst member 10 (such as with an adhesive, weld, cladding, or mechanicalfastener), the second high entropy alloy may be secured to the secondmember 20 (such as with an adhesive, weld, cladding, or mechanicalfastener), the first member 10 may then be positioned with respect tothe second member 20 with the first high entropy alloy positionedadjacent to the second high entropy alloy, and spot welding as shown inFIG. 1 may be performed to form a weld nugget that may include one ormore portions of the first member 10, the first high entropy alloy, thesecond high entropy alloy, and the second member 20 to join the firstmember 10 to the second member 20.

It is to be understood that the first member 10 and the second member 20are not limited to the examples described herein. In a non-limitingexample, the first member 10 can be comprised of steel, aluminum andaluminum alloys, magnesium and magnesium alloys, and titanium andtitanium alloys, and the second member 20 may be comprised of steel,aluminum and aluminum alloys, magnesium and magnesium alloys, andtitanium and titanium alloys. Aluminum alloys include, but are notlimited, to cast and wrought alloys. Illustrative examples of steelinclude advanced high-strength steels such as dual phase steels 980grade, and ultra-high strength steels. It is also to be understood thatthe first member 10 and the second member 20 can be the same alloys, butdifferent grades. In an illustrative example, the first member 10 may bea 7000 series aluminum alloy such as 7075, and the second member 20 maybe a 6000 series aluminum alloy such as 6061. In another illustrativeexample, the first member 10 may be a first steel composition such asUsibor® 1500P (commercially available from Arcelor Mittal), and thesecond member 20 may be a second steel composition such as JAC980YL thatis different than the first steel composition. It is also to beunderstood that either or both of the first member 10 and the secondmember 20 may be coated. For example, the first member 10 may be anultra-high strength steel such as Usibor® 1500P (commercially availablefrom Arcelor Mittal) with an Al—Si coating, the second member 20 may bean aluminum alloy such as 7075 or 6061, and optionally the third member30 includes at least Fe, Al, and Si as principal elements, andoptionally may comprise Fe, Al, Mn, Si, Cr, and Ni as principal elementsand include B as a principal minor element. The composition of Usibor®1500P is summarized below in weight percentages (the rest is iron (Fe)and unavoidable impurities):

C Mn Si Ni Cr Cu S P Al V Ti B 0.221 1.29 0.28 0.013 0.193 0.01 0.0010.018 0.032 0.005 0.039 0.0038

In a non-limiting example, the first member 10 may be a zinc-platedsteel such as JAC980YL, the second member 20 may be an aluminum alloysuch as 7075 or 6061, and the third member 30 optionally includes atleast Fe, Al, and Si as principal elements, and optionally may compriseFe, Al, Mn, Si, Cr, and Ni as principal elements and include B asprincipal a minor element. JAC980YL is a high-performance high-tensilesteel defined according to the Japan Iron and Steel Federation Standard.

In another non-limiting example, both the first member 10 and the secondmember 20 may be a zinc-plated steel such as JAC980YL, and the thirdmember 30 optionally includes at least one of Cu, Co, and Zn as aprincipal major element, and optionally may comprise at least one of Cuand Co as a principal major element and Zn as a principal minor element.

The high entropy alloy of the third member 30 may comprise a firstprincipal element that is the same as the metal or the base metal of thefirst member 10, and optionally comprises a second principal elementthat is the same as the metal or the base metal of the second member 20.For example, the first member 10 may comprise an aluminum alloy, thesecond member 20 may comprise steel, and the high entropy alloy of thethird member 30 may comprise at least Al and Fe as principal elements.In a non-limiting example, the first member 10 is a coated steel, thesecond member 20 is an aluminum alloy, and the high entropy alloy of thethird member 30 includes Fe, Al, and a third element as a principalelement that is included in the coating of the steel of the secondmember 20. In a non-limiting example, the coating includes Si and thehigh entropy alloy of the third member 30 includes Fe, Al, and Si asprincipal elements. In another non-limiting example, the coatingincludes Zn and the high entropy alloy of the third member 30 includesFe, Al, and Zn as principal elements. Optionally, the high entropy alloyof the third member 30 includes five principal elements: Al, Fe, Mn, Cr,and Ni. Optionally, the high entropy alloy of the third member 30includes six principal elements: Al, Fe, Mn, Si, Cr, and Ni.

In another non-limiting example, the first member 10 may be a coatediron and/or a coated steel, the second member 20 may be a coated ironand/or a coated steel that is the same or different from the coated ironand/or coated steel of the first member 10, and the third member 30 maycomprise a high entropy alloy as described herein. In this example, thecoating may be a Zn coating, wherein the Zn coating may optionally beprovided by galvanizing the iron and/or steel to provide galvanized ironand/or galvanized steel, respectively, and/or by galvannealing the ironand/or steel to provide a galvannealed iron and/or galvannealed steel,respectively. It should be understood that in resistance spot weldingprocesses of galvannealed iron and/or galvannealed steel without a thirdmember as described herein, the low melting point of the Zn coating, aswell as the applied load by the welding electrodes, may cause diffusionof Zn into the iron and/or steel, leading to LME cracking. By providinga third member 30 as described herein, the high entropy alloy may absorbfree Zn during welding and thus prevent Zn from segregating into theweld zone of the first and second members. In this way, high jointquality may be achieved.

In another non-limiting example, the high entropy alloy of the thirdmember 30 may comprise a first principal element that is the same as thebase metal of the first member 10, a second principal element that isthe same as a second or a third most abundant element of the firstmember 10, a third principal element that is the same as the base metalof the second member 20, a fourth principal element that is the same asa second or a third most abundant element of the second member 20,and/or a fifth principal element that is the same as a coating of thefirst member 10 and/or the second member 20. For example, the firstmember 10 may be a 6061 aluminum alloy that contains Mg and Si as thesecond and third most abundant elements, the second member 20 may beJAC980YL zinc-coated steel that contains Mn and Cr as the second andthird most abundant elements, and the third member 30 includes Al, Fe,Si, and Mn, optionally the third member 30 includes Al, Fe, Si, and Cr,and optionally the third member includes Al, Fe, Si, Mn, and Cr. Inanother example, the first member 10 and the second member 20 may beJAC980YL zinc-coated steel that contains Mn and Cr as the second andthird most abundant elements, and the third member 30 includes Fe. Inthis example, the third member may also optionally comprise Mn, Ni, Co,Cu, Cr, and/or Zn, as described herein.

As shown in FIG. 2, the third member 30 comprising the high entropyalloy may be deposited on the first member 10 and the second member 20to form the multi-material component 5. The third member 30 may bedeposited on the first member 10 and the second member 20 withoutmelting the first member 10 or the second member 20. As shown in FIGS.3A and 3B, the high entropy alloy (or a high entropy alloy precursorcomposition) may be provided in the form of a welding consumable 140,and a heat source may be applied to the welding consumable 140 todeposit the third member 30 comprising the high entropy alloy on thefirst member 10 and the second member 20. It is to be understood,however, that a portion of one or both of the first member 10 and thesecond member 20 may be melted at the location where the third member 30is deposited. Non-limiting examples of methods that may be used todeposit the third member 30 comprising the high entropy alloy on thefirst member 10 and the second member 20 include at least one ofelectron beam welding, laser beam welding (FIG. 4), plasma arc welding,gas metal arc welding (FIG. 5), gas tungsten arc welding (FIG. 6), lasercladding (FIGS. 7A and 7B), flux cored arc welding, and submerged arcwelding.

The high entropy alloy (or high entropy alloy precursor composition) ofthe welding consumable 140 may include any composition described abovefor use with any of the first member 10 and second member 20combinations described above. In an illustrative example, the weldingconsumable 140 may comprise a first principal element that is the sameas the metal or the base metal of the first member 10, and optionallycomprises a second principal element that is the same as the metal orthe base metal of the second member 20. For example, the first member 10comprises an aluminum alloy, the second member 20 comprises steel, andthe high entropy alloy (or high entropy alloy precursor composition) ofthe welding consumable 140 comprises at least Al and Fe as principalelements. In another example, the first member 10 and/or the secondmember 20 may each comprise Fe or steel, and the high entropy alloy (orhigh entropy alloy precursor composition) of the welding consumable 140comprises at least Fe as a principal element. In another example, thefirst member 10 and/or the second member 20 may each comprisegalvannealed Fe and/or galvannealed steel, and the high entropy alloy(or high entropy alloy precursor composition) of the welding consumable140 comprises at least Fe as a principal element and optionally Zn as aprincipal major element or a principal minor element. In anotherexample, the first member 10 and/or the second member 20 may eachcomprise Fe and/or steel, each independently with or without a Zncoating as described herein, and the high entropy alloy (or high entropyalloy precursor composition) of the welding consumable 140 comprises atleast one of Cu, Co, and Zn as a principal major element, and optionallyat least one of Cu and Cu as a principal major element and Zn as aprincipal major element or a principal minor element. Optionally, thehigh entropy alloy (or high entropy alloy precursor composition) of thewelding consumable 140 includes five principal elements: Al, Fe, Mn, Cr,and Ni. Optionally, the high entropy alloy (or high entropy alloyprecursor composition) of the welding consumable 140 includes four ormore principal elements, optionally five or more principal elements,optionally six or more principal elements, and optionally seven or moreprincipal elements, wherein the principal elements are selected from thegroup consisting of Fe, Mn, Ni, Co, Cu, Cr, and Zn. Optionally, the highentropy alloy (or high entropy alloy precursor composition) of thewelding consumable 140 includes one principal minor element as describedherein.

As shown in FIGS. 3A and 3B, the welding consumable 140 may be a fillerwire including a base filler material 141 comprising the high entropyalloy or a high entropy alloy precursor composition that forms a highentropy alloy when melted. A shield or flux 142 may be provided aroundthe core base filler material 141. Alternatively, the flux 142 may bedisposed in the core of the filler wire (not shown). Flux 142 is used toprotect the weld area from oxidation. For example, the flux 142 may forma protective slag over the weld area to shield the weld area from theatmosphere and/or form carbon dioxide to protect the weld area. Such aflux coating is generally known and often used with self-shieldingelectrodes. Although the welding consumable 140 is primarily describedherein with respect to a filler wire, the welding consumable 140 is notlimited to such configuration and may take any suitable form including,but not limited to, foil, strip, plate, or powder forms. It is also tobe understood that the welding consumable 140 may be made by any methodused to make welding consumables or to form high entropy alloys. In anon-limiting example, the welding consumable 140 may be produced byusing liquid-phase methods include arc melting and induction melting, byusing solid-state processing such as the use of a high-energy ball mill,gas-phase processing including sputtering, or by thermal spraying, lasercladding, or electrodeposition. In a non-limiting example, the weldingconsumable may be a filler wire having a diameter of 0.8 mm to 5.0 mm,optionally 0.8 mm to 1.75 mm, optionally 1.50 mm to 2.5 mm, optionally4.50 mm to 5.00 mm, optionally 1.0 mm, optionally 1.2 mm, optionally,1.6 mm, optionally 2.0 mm, optionally 2.4 mm, and optionally 4.76 mm.

As shown in FIG. 4, a laser beam 110 may be applied from an energysource to melt the welding consumable 140 to join the first member 10 tothe second member 20 with the high entropy alloy. As shown in FIG. 5, ametal inert gas welding device 200 is provided that is capable ofmelting the welding consumable 140 to join the first member 10 to thesecond member 20 with the third member 30 comprising the high entropyalloy. As shown in FIG. 6, a tungsten inert gas welding device 250 isprovided with a non-consumable electrode 251 capable of melting thewelding consumable 140 to join the first member 10 to the second member20 with the third member 30 comprising the high entropy alloy.

As shown in FIGS. 7A and 7B, the third member 30 may be applied to thefirst member 10 and the second member 20 as a cladding or weld overlay.As shown in FIG. 7A, a laser 120 may be provided for applying a laserbeam to the welding consumable 140 (in the form of a wire) to form amelt pool 35 of the high entropy alloy that solidifies to form the thirdmember 30 to join the first member 10 to the second member 20. As shownin FIG. 7B, the laser 120 may apply a laser beam to the weldingconsumable 140 that is in the form of a powder. The powder weldingconsumable 140 is fed via an injection nozzle 143 to the laser 120 wherea laser beam contacts the powder welding consumable 140 to form a meltpool 35 of the high entropy alloy that solidifies to form the thirdmember 30. It is to be understood that the powder welding consumable 140may be a powder form of the high entropy alloy, or may be a mixture ofmetal or metal alloy powders that are melted by the laser 120 to formthe high entropy alloy. Although the cladding or overlaying of the thirdmember 30 is described with respect to a laser 120, it is to beunderstood that the cladding or overlaying of the third member 30 can beapplied using any suitable process including, but not limited to, manualmetal arc welding, gas tungsten arc welding, gas metal arc welding,submerged arc welding, flux cored arc welding, and plasma transferredarc welding.

As shown in FIG. 8, a high energy heat source may be provided forperforming any of brazing, cladding, building up, filling, hard-facingoverlaying, and joining/welding applications with the welding consumable140. The high energy heat source is capable of heating one of the firstmember 10, the second member 20, the welding consumable 140, or anycombination thereof to form the melt pool 35. The high energy heatsource can be a laser subsystem 130/120 that includes a laser device 120and a laser power supply 130 operatively connected to each other. Thelaser 120 is capable of focusing a laser beam 110 onto one of the firstmember 10, the second member 20, and the welding consumable 140, or anycombination thereof, and the power supply 130 provides the power tooperate the laser device 120. The laser subsystem 130/120 can be anytype of high energy laser source, including but not limited to carbondioxide, Nd:YAG, Yb-disk, YB-fiber, fiber delivered, or direct diodelaser systems. Further, white light or quartz laser type systems can beused if they have sufficient energy. Although the high energy heatsource is described with respect to a laser system, it is to beunderstood that this reference is exemplary and any high intensityenergy source may be used. Other non-limiting examples of the highenergy heat source may include at least one of an electron beam, aplasma arc welding subsystem, a gas tungsten arc welding subsystem, agas metal arc welding subsystem, a flux cored arc welding subsystem, anda submerged arc welding subsystem.

A filler wire feeder subsystem may be provided that is capable ofproviding at least one welding consumable 140 to the vicinity of thelaser beam 110. It is understood that the molten puddle, i.e., melt pool35, may be considered only part of the high entropy alloy from thewelding consumable 140, or part of one or both of the first member 10and the second member 20 with the high entropy alloy from the weldingconsumable 140. The filler wire feeder subsystem may include a fillerwire feeder 150, a contact tube 160, and a wire power supply 170. Thewire welding power supply 170 may be a direct current (DC) power supply(that can be pulsed, for example), although alternating current (AC) orother types of power supplies are possible as well. The wire weldingconsumable 140 is fed from the filler wire feeder 150 through thecontact tube 160 toward the first member 10 and/or the second member 20and extends beyond the tube 160. During operation, the extension portionof the wire welding consumable 140 may be resistance-heated by anelectrical current from the wire welding power supply 170, which may beoperatively connected between the contact tube 160 and the one or bothof the first member 10 and the second member 20.

Prior to its entry into the weld puddle 35, the extension portion of thewire welding consumable 140 may be resistance-heated such that theextension portion approaches or reaches the melting point beforecontacting the weld puddle 35. Because the wire welding consumable 140is heated to at or near its melting point, its presence in the weldpuddle 35 will not appreciably cool or solidify the melt pool 35 and thewire welding consumable 140 is quickly consumed into the melt pool 35.The laser beam 110 (or other energy source) may serve to melt some ofone or both of the first member 10 and the second member 20 to form theweld puddle 35. Optionally, the laser beam 110 (or other energy source)may serve to melt only the wire welding consumable 140 to form the weldpuddle 35. The system may also include a sensing and control unit 195.The sensing and control unit 195 can be operatively connected to thepower supply 170, the wire feeder 150, and/or the laser power supply 130to control the welding process.

In a non-limiting example, the multi-material component 5 is anautomotive component. In an illustrative example, the first member 10 isan aluminum alloy roof and the second member 20 is a steel vehicle body.In another illustrative example, the multi-material component 5 is anyautomotive component fabricated by joining the first member 10 and thesecond member 20 as described herein, wherein one or both of the firstand second members comprise iron and/or steel having a Zn coating asdescribed herein and are joined via resistance spot welding.

In a non-limiting example as shown in FIGS. 9A and 9B, themulti-material component 5 may include a first member 10 that is analuminum alloy roof rail and a second member 20 that is a steelB-pillar. The first member 10 may be secured to the second member 20with the third component 30 comprising the high entropy alloy using anyof the methods disclosed herein. As shown in FIGS. 9A and 9B, a firstend 25 of the second member 20 may overlap a portion 33 of the firstmember 10 that extends downwardly toward a side sill (not shown) thatmay be comprised of either an aluminum alloy or steel. An edge 37 of thefirst end 25 of the second member 20 may be welded to the first member10 with the welding consumable 140 to deposit the third member 30comprising the high entropy alloy on the first member 10 and the secondmember 20. In addition to, or alternatively, the third member 30 may bein the form of a plate, a sheet, or the like, and the first member 10and the second member 20 may be joined to the third member 30 by one ormore welds, mechanical fasteners, adhesives, or any combination thereof.In a non-limiting example, the third member 30 is a sheet that ispositioned between the first end 25 of the second member 20 and theportion 33 of the first member 10, and the first member 10 and thesecond member 20 are then spot welded to the third member 30 with aresistance spot welding device 40.

While, for purposes of simplicity of explanation, the methods have stepsdescribed as executing serially, it is to be understood and appreciatedthat the present disclosure is not limited by the illustrated order, andsome steps could occur in different orders and/or concurrently withother steps from that shown and described herein.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Also thatvarious presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art which are also intended to beencompassed by the following claims.

EXAMPLES Example I: Tensile-Shear Test for Resistance Spot Welding Using370 μm Thick HEA Interlayers

A high entropy alloy consisting of Fe, Mn, Ni, and Co was prepared usingvacuum arc melting. Multiple high entropy alloy foils each having athickness of 370 μm were prepared by rolling then ground to a finalthickness. Six weld sets were then formed by welding two of thegalvannealed steel sheets via resistance spot welding within thefollowing parameters: 60 Hz, 8.5 K. amps, 26 cycles, and 770 pounds.Weld sets N-1, N-2, and N-3 were formed without a high entropy alloy,and weld sets H-1, H-2, and H-3 were formed with the high entropy alloyprovided as an interlayer between the two galvannealed steel sheetsprior to welding. FIG. 10 shows the load (KN) vs. displacement (mm) foreach sample studied in the Tensile-Sear Test described in Example I.

Example II: Fracture Surface of Spot Welds Using 370 μm Thick HEAInterlayers after Tensile-Shear Test

FIG. 11 shows the optical macrographs of the fracture surface and topsurface of the weld spots of the upper steel sheet of samples N-1, N-2,and N-3. Interfacial shear mode was detected in each of the samples.FIG. 12A shows the optical macrographs of the fracture surface and topsurface of the weld spots of the upper steel sheet of samples H-1, H-2,and H-3. FIG. 12B is a magnified portion of the top surface of the weldspot of sample H-2. A mixed fracture mode (pull out+ interfacial shear)was detected in each of the samples. FIG. 13 is a schematic showing thetensile stress axis relative to the demonstrated plan views shown inFIGS. 11 and 12.

Based on Examples I and II, it was concluded that introducing the highentropy alloy interlayer resulted in a smaller spot weld area andpartially (50%) pull out fracture mode instead of 100% interfacialfracture mode as observed in the samples without a high entropy alloy.

Example III: Tensile-Shear Test for Resistance Spot Welding Using 220 μmThick HEA Interlayers

A high entropy alloy consisting of Fe, Mn, Ni, and Co was prepared usingvacuum arc melting. Multiple high entropy alloy foils each having athickness of 220 μm were prepared by rolling then ground to a finalthickness. Eight weld sets were then formed by welding two of the steelsheets via resistance spot welding within the following parameters: 60Hz, 9.5 K amps, 26 cycles, and 1000 pounds. Four weld sets were formedwithout a high entropy alloy interlayer, and four weld sets were formedwith the high entropy alloy foil provided as an interlayer between thetwo steel sheets prior to welding. FIG. 14A shows the load (k. N) vs.displacement (mm) for each sample studied in the Tensile-Sear Testdescribed in Example III. FIG. 14B shows the average fracture load forboth of sample groups. From FIGS. 14A and 14B, it can be observed thatby decreasing the thickness of the HEA interlayer down to 220 μm theaverage fracture load for samples with HEA interlayer increased by 10%more than that of the other samples without interlayers. This could beattributed to decreasing the stress concentration between the two weldedsteel sheets by using thinner interlayers. Also, there is moreconsistency in the tensile properties (strain hardening) with using theHEA interlayers as shown by the closer red curves in FIG. 14A andslightly narrower fluctuation in FIG. 14B.

Example IV: Fracture Surface of Spot Welds Using 220 μm Thick HEAInterlayers after Tensile-Shear Test

FIG. 15 shows the optical macrographs of the two fracture surfaces(mirror images) of the spot welds for upper and lower steel sheets ofsamples N-4, N-5, N-6, and N-7. As observed before, fully interfacialshear fracture mode was seen in all samples. FIG. 16 shows of the twofracture surfaces (mirror images) of the spot welds for upper and lowersteel sheets of samples H-4, H-5, H-6, and H-7. For this samples group,two samples (H-4 and H-5) failed by 100% pull out fracture mode whilethe other two samples failed majorly by interfacial shear mode. FIG. 13is a schematic showing the tensile stress axis relative to thedemonstrated plan views shown in FIGS. 15, and 16.

Based on Examples III and IV, it was determined that the samplescontaining the high entropy alloy interlayer showed higher fracture loadas well as a more consistent tensile curve compared to the sampleswithout the high entropy alloy interlayer.

Example V: ThermoCalc Simulation of Equilibrium Phase and ScheilSolidification Diagrams

ThermoCalc was used to prepare an equilibrium phase diagram and a Scheilsolidification diagram for an example HEA consisting of Fe, Mn, Ni, Co,and Zn. FIG. 17 shows the phase diagram, and FIG. 18 shows the Scheilsolidification diagram.

As seen in FIG. 17, the phase diagram showed the dominance of the FCCphase. As seen in FIG. 18, the Scheil solidification diagram quantifiedthe mole fraction of liquid and FCC phase to be more than 0.8. Thecalculation also predicted the presence of gamma phase in accordancewith the equilibrium phase diagram. The composition of gamma phase wascalculated to be 25 wt. % Ni-75 wt. % Zn, as shown in FIG. 19. (FIG. 19shows the chemical composition of gamma phase.) Among the five knownphases for zinc-nickel alloys stated in the literature, most of thesealloys are utilized in the application of corrosion resistance platingη-(1 wt. % Ni), α, and β-(30 wt. % Ni, known as the nickel rich phase),which is the closest composition to what was calculated. Based on theplating application, they were not expected to be too brittle phasesthat cause a loss in toughness. β-(Ni3Zn22) 11 wt. % Ni and γ-(Ni5Zn21)17.6 wt. % Ni are the other two phases considered to be Zn-rich.

Example VI: DICTRA Diffusion Modeling of HEA

DICTRA, a module in the ThermoCalc software package for the simulationof diffusion controlled transformations in multicomponent systems, wasused to model an example HEA consisting of Fe, Mn, Ni, Co, and Zn. TheHEA database package TCHEA3 and MOBHEA1 were used under the assumptionthat there were two components, the HEA on the left side and steel onthe right, and that the calculated amount of Zn from the galvanizinglayer in the nugget and HAZ (vaporized or melted) was compensated intothe HEA initial composition profile, as shown in FIG. 20A. (FIG. 20Ashows the initial chemical composition profile.)

The composition of each element was defined through the followingequation:

F(x)=C+D*erf((X−E)/F),where:

C=(X₁+X₂)/2, where X₁ and X₂ are the concentrations of each element inthe HEA side and iron side, respectively

D=X ₂ −C

E=location of the boundary between the two components (at 100 μm)

F=sharpness of the boundary (was set to be 5 μm).

The Zn composition in the HEA was set to be higher than its value in thedesigned equiatomic alloy (0.2 mole Zn) to take in all the incoming Zn(˜2 mg) from the coating layer so that the HEA was assumed to beconstituted of 0.27 mole Zn (and 0.1825 mole from each of the other fourelements)

The steel composition was assumed to be 100% iron. The thickness of eachcomponent was assumed to be 100 μm. Double geometric mesh was utilizedto have finer mesh around the centerline (interdiffusion region).

The phases that were introduced to the model were based on the Scheilsolidification diagram. A simplified thermal profile was introduced tothe model to mimic the literature data to simulate a welding processover a time of one second with a maximum temperature of 2100° C.

FIG. 20B shows the thermal profile for the diffusion modelling.

FIGS. 21A and 21B show the diffusion behavior of the HEA vs. steel(assumed 100% Fe). Specifically, FIG. 21A shows the composition profileafter diffusion simulation, and FIG. 21B shows the predicted phases. Ascan be seen in these figures, Zn appeared to be the slowest elementdiffusing into the steel, as it stops after a distance of ˜25 μm intothe steel side. Co appeared to be the fastest element diffusing into thesteel, followed by Ni and Mn. Potential diffusion boundaries appeared at25 or 40 μm in the steel side. In FIG. 21B, phases predicted by themodel to be present in the HEA (FCC+gamma) matched the phases calculatedfrom the Scheil solidification diagram, while steel was presented asBCC, as only Fe was present in the steel side in this simulation.

DICTRA diffusion modelling was also conducted for a Zn—Fe couple withoutthe addition of the HEA to simulate the original condition. The samethermal profile as described above was applied except that the initialchemical composition profile was set for 100 wt. % Zn vs. 100 wt. % Fewith a 100 μm thickness on each side. Much deeper diffusion of both Znand Fe into each other was observed. FIGS. 22A and 22B show thediffusion behavior of the Zn—Fe couple vs. steel (assumed 100% Fe).Specifically, FIG. 23A shows the composition profile after diffusionsimulation, and FIG. 22B shows the predicted phases. Two phases wereidentified: Gamma_FeZn and a HCP phase.

Example VII: DICTRA Diffusion Modeling of HEA

The process described in EXAMPLE VI was repeated for an example HEAconsisting of Fe, Mn, Ni, and Co. FIG. 23 shows the diffusion behaviorof the HEA vs. steel (assumed 100% Fe), specifically, the compositionprofile after diffusion simulation. As seen in FIG. 23, the Zn diffusionstopped after 10 μm into the Fe side.

Example VIII: Optical Microscopy of RSW Samples

Four steel samples were prepared in order to study the effects of an HEAon a resistance spot welding (RSW) process. First, a control sample wasprepared by welding two steel sheets using welding parameters of 9.5 kA,26 cycles, and 800 pounds. A dome-shaped welding electrode (TB-25-TUFF)was used. No HEA was used in the control sample.

One inventive sample was also prepared using two steel sheets and thewelding parameters described above with using the same welding electrode(dome shaped) in order to avoid foil separation away from the steelsheets as the electrode pressed on the joint. The inventive sampleadditionally contained an HEA foil on each of the two outer surfaces ofthe spot weld enclosing the top and bottom of the joint. The HEAconsisted of Fe, Ni, Co, and Mn.

FIG. 24A is a photograph of two cross sections of the control sample.FIG. 24B shows optical micrographs of the control sample at thelocations designated 1, 2, 3, and 4 in FIG. 24A. As shown in FIG. 24B,the optical micrographs show type-1 LME cracks occurring at the edge ofthe electrode indentation on the steel sheet (weld shoulder). The cracklength range was about 10 to 100 μm.

FIG. 25A shows a photograph of two cross sections of the inventivesample. FIG. 25B shows optical micrograph of the inventive sample at thelocations designated 1, 2, 3, and 4 in FIG. 25A. As shown in FIG. 25B,the optical micrographs show the absence of LME cracks in the inventivesample, especially at the same locations where LME cracks were observedin the control sample.

What is claimed is:
 1. A multi-material component comprising: a firstmember; a second member; and a third member joining the first member tothe second member, wherein at least one of the first member and thesecond member comprises iron and/or steel having a coating, wherein thecoating comprises Zn, wherein the third member comprises a high entropyalloy comprising at least four principal major elements, and wherein oneof the at least four principal major elements is Co.
 2. Themulti-material component of claim 1, wherein one of the at least fourprincipal major elements is Cu.
 3. The multi-material component of claim1, wherein one of the at least four principal major elements is Fe. 4.The multi-material component of claim 1, wherein one of the at leastfour principal major elements is Mn.
 5. The multi-material component ofclaim 1, wherein one of the at least four principal major elements isNi.
 6. The multi-material component of claim 1, wherein one of the atleast four principal major elements is Zn.
 7. The multi-materialcomponent of claim 1, wherein the high entropy alloy comprises at leastone principal minor element, wherein the at least one principal minorelement comprises Zn.
 8. The multi-material component of claim 1,wherein two of the at least four principal major elements are Cu and Zn.9. The multi-material component of claim 1, wherein one of the at leastfour principal major elements is Cu, and wherein the high entropy alloyfurther comprises at least one principal minor element, the at least oneprincipal minor element comprising Zn.
 10. The multi-material componentof claim 1, wherein both of the first member and the second membercomprise iron and/or steel having a coating, wherein the coatingcomprises Zn.
 11. The multi-material component of claim 1, wherein thethird member is at least partially positioned between the first memberand the second member, and wherein the first member is spot welded tothe third member and the second member is spot welded to the thirdmember.
 12. The multi-material component of claim 1, wherein the highentropy alloy comprises a mixing entropy of greater than 1.5R.
 13. Amulti-material component comprising: a first member comprising a firstmetal or a first metal alloy; a second member comprising a second metalor a second metal alloy; and a third member joining the first member tothe second member, wherein at least one of the first metal or firstmetal alloy and the second metal or second metal alloy comprises ironand/or steel having a coating, wherein the coating comprises Zn, whereinthe third member comprises a high entropy alloy comprising at least fourprincipal major elements, wherein one of the at least four principalmajor elements is Cu.
 14. The multi-material component of claim 13,wherein one of the at least four principal major elements is Fe.
 15. Themulti-material component of claim 13, wherein one of the at least fourprincipal major elements is Mn.
 16. The multi-material component ofclaim 13, wherein one of the at least four principal major elements isNi.
 17. The multi-material component of claim 13, wherein one of the atleast four principal major elements is Zn.
 18. The multi-materialcomponent of claim 13, wherein the high entropy alloy comprises at leastone principal minor element, wherein the at least one principal minorelement comprises Zn.
 19. The multi-material component of claim 13,wherein both of the first member and the second member comprise ironand/or steel having a coating, wherein the coating comprises Zn.
 20. Themulti-material component of claim 13, wherein the third member is atleast partially positioned between the first member and the secondmember, and wherein the first member is spot welded to the third memberand the second member is spot welded to the third member.
 21. Themulti-material component of claim 13, wherein the high entropy alloycomprises a mixing entropy of greater than 1.5R.
 22. A method of makinga multi-material component comprising: providing a first member;providing a second member; and joining the first member to the secondmember with a third member comprising a high entropy alloy to form themulti-material component, wherein at least one of the first member andthe second member comprises iron and/or steel having a coating, whereinthe coating comprises Zn, wherein the high entropy alloy comprises atleast four principal major elements, and wherein one of the at leastfour principal major elements is Co, Cu, or Zn.
 23. The method accordingto claim 22, wherein both of the first member and the second membercomprise iron and/or steel having a coating, wherein the coatingcomprises Zn.